What does the Saunier Duval 21 fault code mean?

Your boiler has stopped working because the water pressure inside the system is currently too low to operate safely.

How much does it cost to fix Saunier Duval error code 21?

Typical repair cost for the Saunier Duval 21 fault is £80-150 including labour.

Locate the filling loop (a flexible silver hose) underneath the boiler.

You have insufficient water pressure (0.5 bar or lower).

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Six most common causes of dropping pressure.

Step-by-step using the filling loop.

7 signs repair isn't worth it anymore.